Aluminum body for magnetic chucks



4 SHEETS-SHED I.

F. L. SIMMONS. ALUMINUM BODY FOR MAGNETIC CHUCKS.

Patented Oct 31, 1922.

Y wlm- APPLICATION FILED FEB. 26. I9I8.

TTORNE Y;

R. m m w F. L. SIMMONS. ALUMINUM BooY FOR MAGNETIC cHUcKs.

APPLICATION FILED FEB. 26, 1918.

MTM/MNE Y; v

F. L. SIMMONS.

ALUMINUM BUBHUR MAGNETIC CHUCKS.

APPLlcATloN mso ris. 2s. 191m 1,433,568. l .Patented oct. 31,1922.

4 SHEETS-SHEU 3.

NVEN'TOR.

BY 2 ATTOREEY F. L. SIMMUNS.

ALUMINUM BODY FOR MAGNETIC CHUCKS.

APPLICATION FILED FEB. 26, 1918.

Patented Oct. 31, 1922..

4 SHEETS-SHED 4.

BY 3 fbg ATTORNEY Patented Oct. 31, 1922.

UNITEDv STATES l 1,433,568 PATENT OFFICE.

FRANK L. SIMMONS, OF WOONSOCKET, RHODE ISLAND, ASSIGNOR T0 THE TAFT-PEIRCE MANUFACTURING C0., OF WOONSOCKET, RHODE ISLAND, A CORPORA- TIONOF RHODE ISLAND.

ALUMINUM BODY FOR MAGNETIC CHUCKS.

Application led February 26, 1918.

To all whom t may concern.'

Be it'known that I, FRANK L. SIMMONS, a citizen of the United States,residing at Woonsocket, in the county of Providence, State ofRhodelsland, have invented certain new and useful Improvements inAluminum Bodies for Magnetic Chucks, of which the following is aspecification.

This invention relates broadly to electrical appliances, and moreespecia ly to a magnetic chuck.

T he principal object of the present lnvention is to provide a magneticchuck whereln the pole pieces and cores for the electromagnets toenergize the pole pieces are made from magnetizable material, and theentire housing and support for the pole pieces of the face plate is madefrom non-magnetic material.

Another and equally important object of the present invention is amagnetic chuck wherein the core pieces for the energizingelectro-magnets are supported in place in the housing by molding thehousing around the bases of the core pieces.

Another equally important object of the present invention is a faceplate for magnetic chucks wherein the core pieces are supported in aface plate frame of non-magnetizable material vwhich is molded aroundthe pole ypieces in such manner as to sustain,

the pole pieces and form the complete face plate of two metals, amagnetic metal comprising the pole pieces, and a non-magnetic metalcomprising the frame.

A further and likewise import-ant object of the present invention is amagnetic chuck with a molded body portion of non-magnetic material,comprising a box to enclose the electro-magnetic energizing units, and aface plate carrying pole pieces andt adapted to close said box with thepole pieces in contact with the said electro-magnetic units, wherebythere is a single water-tight joint l in the construction of the housingfor the energizing element.

More specifically the present invention comprises an electro-magneticchuck having a housing of aluminum or'other suitable non-magnetic metal.which is molded around the core pieces for the electro-magnetic units insuch manner as to render the core pieces andthe housing substantiallyintegral, and wherein the framework of the face plate is Serial No.219,237.

likewise aluminum or other suitable nonmagnetic material in which isembedded a plurality of spaced apart individual ole pieces in suchmanner that the face p ate likewise comprises a substantially unitarystructure.

.A further object of the present invention 1s to provide a magneticchuck wherein the electro-magnetic member comprises a plurality of polepieces extending from a base and with the base embedded in the metal ofthe housing in such manner that the electro-magnetic members and thehousing are substantiallyintegral, and with the face plate provided withthe pole pieces in direct contact with the ends of the pole pieces ofthe electro-magnetic memberso that the complete magnetic chuck whenassembled comprises a substantially continuous metal structure from thesurface of a face plate pole )iece through to the bottom surface of theh is constructed to withstand heavy pressure directly on the polepieces. The preceding object of the present invention is an improvementon certain features of my application for patent Serial No. 190,689,filed September 1l, 1917.

A still further and equally important object of the present invention isto provide a magnetic chuck havin a face plate composed of pole piecesof tree-like conformation comprising a body portion and extensions onopposite sides of said body portion, with the extensions of one polepiece interspersed between the extensions on the adjacent pole piece andelectro-magnetic means formagnetizing adjacent pole pieces as oppositemagnetic poles.

Another object of the present invention is a magnetic chuck having theentire face plate composed of transverse interspersed pole piecessupported in non-magnetic material'whereby the effective magnetism isconcentrated over the work face of the face plate.

Other and further objects of the present invention will in part beobvious and will in art be pointed out hereinafter in the specicationfollowing by reference to the accompanying drawings wherein like partsare ousing whereby the chuck represented by like characters throughoutrthe-surface plate pole pieces.

chuck showing a portion of the face plate removed.

Fi re 2 is a section taken on line A- of Flgure l. i

Figure 3 isa sectional view;A taken lon lme B-B Figure I.

Figure 4f is a perspective view of one core piece for the electro-magnetmember andfshows the core` pieces extending from the base'.

Figure 5 is a perspective view of a coil adapted to slip over the corepole pieces.

Figure 6 is a perspective view of one of Figure 7 is a plan view of thepole piece shown in Figure 6.

Figure 8 is an elevational view of this pole piece. c

Figure 9 is an end view of the same pole piece.

Figure 10 is a diagrammatic illustration of' the wiring as connected fora 220 volt circuit. c

Figure 11 is a diagrannnatic view of the wiring as connected for a 110volt circuit.

Figure 12 isa m-odified'form of face plate pole pieces of suoliconformation that but two dies are necessary to produce the forging forall of' the pole pieces.

Figure 13 is another modified Jform of pole pieces wherein but two diesare required to produce all the pole pieces.

Heretofore in the art it has been customary to utilize the housing forthe coils as one element in the magnetic circuit so that the coil postof the core piece which terminated in pole pieces at the face plate wasone leg of the magnetic circuit and the framework Aor housing, whichcontacted with the. frame of the face plate, was the other leg of themagnetic circuit. Magnetic chucks in substantially all applications foruse are mounted on the'iron or steel beds of machine tools, with the bedof the chuck on the bed of the tool and the work in contact with thecutting or grinding member of the tool.

` Where the lines of magnetism flow around the housing to certain olesin the face plate it is evident that tie magnetic -circuit through thebed of the machine, the frame of the machine, andthe cutting tool, willcarry a certainshunted ymagnetic force. The cutting tools are usuallyhardened steel which when once ma netized becomes a permanent magnet,there ore in this type of magnetic chuck the tools become magnetized andtend to collect chips which very greatly interferes with the properoperat-ion of the tool. It has also become customary heretofore in themagnetic chuck art to rovide face plates with', pole pieces ofrelatively straight sided constructions whereby considerable areas ofthe faceplate have been unei'ective as holdin areas. i

Ihe present invention overcomes the difii- Agated coils which areconstructed to fit over culties with the known prior art by providing amagnetic chuck wherein the magnetizable elements are arranged compactlyand supported rigidly upon but spaced apart from the bed of the machinetool with which the chuck is being used. This may be accomplished invarious ways, the preferred form of construction, however, being toprovide a housing of non-magnetic material, preferably aluminum, whichsupports the operative elements of the chuck. ln the preferredconstruction the'cores for the electromagnetic unit comprise a membermade of special magnet mild steel formed with a base portion and aiplurality of outstanding webs vwhich are transversely arranged upon andat right angles to the base portion with these outstanding webs parallelone to another and being adapted to support elonthese'members so thatthere is an individual 'coil for each pole piece. This constructionenables standardization of parts which facilitates manufacture and alsofacilitates relpairs should any coil become defective. The 90 ase ofthis core pieceis embedded in the base of the housing which may be castaround the core piece to comprise an open rectangular box surounding theelectromagnetic element. `The face plate, which comprises the lid forthis box, is composed of face plate pole pieces .which on their underside areadapted to contact with the' outstanding core pole pieces thatcarry the coils. These face plate4 pole pieces are so 100 constructed asto be formed of dro forgings and preferably .are Swedish or orway ironwhich possesses butlittle residual magnetism so that as soon/"as thecurrent is cut ofi' the magnetism inthe chuck ceases. It is 105particularly desirable that the entire effective magnetized zone of theface plate shall be operative as a holding surface. To this end theface-plate pole pieces are provided on their u per sides with tree-likeconforl mations with the branches from one polev interspersed betweenthe branches of the adjacent pole. A uniform space between thesetree-like conformations is filled with nonmagnetic metal and the linesof magnetic force from one pole piece to another pass through the airover the face plate or when a piece of work of iron or steel is laid onthe face plate, such piece of work comprises an armature through whichthe magnetic cirthe cones are brought substantially to a common plane byinding or other suitable method. Likewise both sides of the face plateare ground Vor similarly treated to provide relatively smooth parallelsurfaces.

Where the parts are ground, as specified,

the aluminum being slightly softer than the core pole pieces, grindsslightly deeper so that when the face plate is bolted in posi.

tion on the housing an intimate contact is made between the face plateole pieces and the core pole pieces and su cient s ace is left betweenthe tops of the side wa ls and the frame for the face plate'to permitintroduction of a thin gasket of paper, or other material, whereby awater-tight joint is provided. lt will also be noted that there is onlyone joint to be waterproofed in order to completely seal the housing.vBy embedding the core piece in the housing of nonmagnetic metal, themagnetic circuit is spaced apart from the bed of the machine tool and atthe same time a. firm metal to metal foundation is established betweenthe work faces and the bed of the machine tool.

Referring to the drawings and more particularly to Figures v1 to 5inclusive, the core piece 1 is preferably cast of special mild magnetsteel and comprises a base 2 having, outstanding ledges 4 and beingprovided with a plurality of parallel pole pieces 5. These core piecespreferably are made up in units with eight pole pieces on each unit and.chucks of various dimensions in length may be manufactured byassembling a plurallty of these core sections preferably end to end. Atsuitable intervals the outstanding ledges are recessed as at 6 toprovide sufficient space between the base ledge and assembly screwswhich will be later re.

ferred to.

In Figure 1 there is illustrated a chuck made up to include two coresections or 16 pole pieces. These core sections are supported in aproper mold and a housing or body of non-magnetic metal, preferablyaluminum, is cast around the pole pieces with the ledges 4 embedded inthe base of the housing and with the sides of the housing spaced apartfrom the core pieces 5 a sufiicient distance to allow clearance for theenerxzing coils, later to be more specifically escribed.

The cast housing is machined to provide a Vfinished article and isformed with ledges 7 on the end of the chuck which ledges are adapted tocomprise members which facilitate the clamping of the chuck to asuitable machine frame. The upper end of the pole pieces 5 and the edgesof the sides of the box or housing l8 are machined and ground to asubstantially common plane. The side walls are provided, in the moldingor by drilling, with suitable openings 9 running from the base of thehousing to the top edge of the side walls and comprising openings forthe assembl screws 10. l

The face plate (Figs. 1, 6 to 9 inclusive) is comprised of a pluralityof pole pieces 11 which preferably are drop forgings of Norway orSwedish iron that are supported by being surrounded with non-magneticmetal, in the present case aluminum, or the like. These pole piecespreferably are tree-like in form having a body 12 from which extendprojections 14 that are substantiall the length and the width equal tothe width of the ody portion. Alternate pole pieces' are of alternateconstruction in such manner that the projections from one pole piece areinterspersed between the projections of the adjacent pole piece with aconstant distance between the outline of the pole pieces at the surfaceof the face plate 5. ln forming these pole pieces by drop forging it isconvenient to provide angular faces 16 and 17 on the ends of the polepieces with projections 18 between the faces 16 and 17. When the polepieces are properly assembled with the edgesI spaced apart, asspecified, in a suitable 'mold or otherwise, the non-magnetic metal,preferably aluminum, is molded aroundthe pole pieces in such manner thatthe pole pieces have their sides completely embedded in this metal andbecause of the conformation of the pole pieces it will be seen that theyare securely held 100 against moving in any direction. Where aluminum isused it is desirable to provide inserts 19 of harder metal, such asiron, to comprise the nuts into which the assembly screws 10 may bethreaded. After the face 105 plate has been formed it is preferablymachined and ground on both the upper and lower surfaces so that theupper surface discloses a conformation of nested three-like pole pieces,(Fig. 1) while the lower surface 110 discloses oval shaped 'pole pieceportions which are adapted to set directly over and in contact with theends of the pole pieces 5 when the face plate is positioned on thehousing as indicated in Figure 2, or the 115 right end portion ofFigure 1. It has been found that in the grinding of the joint`betweenthe face plate and the housing that the aluminum grinds slightly deeperthan the iron so that when the pole pieces in the 120 face plate are incontact with the ends of the pole pieces of the core there is a slightspace between the aluminum frame of the face plate and the side walls ofthe housing. This slight space is desirable in affording 126 sufficientroom to provide a water-proofed paper or other suitable gasket on thisjoint so that when the parts are assembled the face plate pole piecesand the core pole pieces are in contact and the joint between 180 Therelthe housing and the faceplate is Water-V proofed.

As previously stated each core pole plece 5` is adapted to carry anelectro-magnetic 'coil 20 which are of oval cross-sectionand aresuitablyinsulated from the core pleces. These coils are connected (Figs. 10 and11) in such manner that the current flows in one direction around onecoil and in the opposite direction around the adjacent coil. When thechuck is energized it theretoreus clear that a plurality of magneticiclrcurts are establishedU whereby the pole pleces 1 n the face plateare of alternate magnetlc signs, as indicated in Figure 1, and thereturn circuit for tlle'magnetism is completed through the base Y2 ofthe core pieces. This provides a very compact electro-magnetlc unitwhereby the tendency of shunt mag netic circuits is reduced to aminimum.

through the tops of metal work carried on the face of this chuck andwhere the chuck is used on a milling machine, the chips from the cuttermay easily be brushed from the surface of the work. With prior artchucks wherein the cutting tool and machine frame have formed a shuntmagnetic circuit, 1n

Vsubstantially all cases chips stick to the work nals 22 may beindividually connected with the terminals 24whererby the coils areinmultiple and adapted. to be operated'bn a 110-volt circuit. n practiceit may be desirable to accurately position work onthe chuck face and forthis purpose'a back strip 25ct cold rolled steel is fastened to the edgeof the face. plate outside of the pole ,piece Zone. `This back strip ispermanently secured in position by machine screws the heads of which areflush with the top of the back strip. In order to provide an adjustablemember against which work may bev positioned a movable back rest 26 isalso provided. This back rest comprises bifurcated *l legs. 27 which areclamped securely in position by means of stub bolts 28 carried by theback side wall of the chuck. It mayalso'be desirable to reinforce theface plate and to this end brass lscrews 29 may be passed through underthe pole pieces and threaded into the'edge of the aluminum facing forthe face plate, as indicated in dotted lines F i0'. 1.

In order to facilitate manufacture of the is substantially no airleakage' vchucks it may be desirable to provide `the poley piececonfor-mations are indicated in Figures l2 and 13. One die would berequired to produce the end pole pieces 30 and a different die would berequired to produce the intermediate pole pieces '31 or 32 as the casemight be. Attention is particularly directed. to the simplicity andrigidity of the herein disclosed chuck and it is to be noted that thereare but three major elements in the makeup of the device, oneelementccomprising the housing and core piece, the other element beingthe coil sections adapted to lit upon the core pieces and thel thirdelement comprising the face plate constructed to be secured to thehousing.

VRealizing thatmy invention may be carried out in structures other thanthos'e spe.

ciically disclosed herewith I desire that this disclosure be understoodas yillustrative and not to be taken in the limiting sense.

Having thus described my invention, what I claim is: l

l. In a magnetic chuck the combination of uch constructions and l a.housing comprisingan open box of nonmagnetic material, a core piece ofmagnetizable lmaterial partially embedded in lsaid housing, face platepole pieces of magnetizable material, a frame of non-magnetizablematerial embedding and closing the sides of said pole pieces, and coilscarried by said core piece and adaptedwhen energized to magnetize-saidcore piece and said face plate pole ieces.

2. n a magnetic chuck the combination of a housing comprising anopen'box of nonf magnetic material, a-core piece of magnetiz ablematerial partially embedded in said,

housing, face plate pole pieces of Ymagnetizable material, a frame ofnon-magnetizable material embedding and closing the sides of said polepieces, lugs on said pole pieces to restrain said pole pieces frommovement in said material, and coils carried by said core piece andadapted when energized to mag# netize Hsaid core piece and said faceplate pole pieces.

3. In a magnetic chuck the combination of a housing comprising an openbox of nonmagnetic material, a core piece of magnetiza'ble materialhaving the base thereof embedded in the base of said housing, face platepole pieces of magnetizable material, a face plate frame ofnon-magnetizable material completely surrounding the sides of each polepiece and supporting each pole piece in such manner vthat when said faceplate is'in position on said housing the facey plate -pole pieces are incontact with said core piece, and energizing coils adapted'to be carriedby said core piece.

lll

edges of the sides of the said pole 4. In a magnetic chuck thecombination of a housing comprising an open box of aluminum, a corepiece 'of magnetizable material having the base thereof embedded in thebase of said housing, face plate pole pieces of magnetizable material, aface plate -frame of aluminum completely surrounding the sides ofveachpole piece and supporting each pole piece in such manner that when saidface plate is in position on said housing the face plate pole pleces arein contact with said core piece, and energizing coils adapted tobecarried by said core piece.

5. In a magnetic chuck the combination of a housing comprising an openbox of nonmagnetic material, a core piece, a base on said core piece,pole pieces 'outstanding from said base, a face plate comprising a frameof non-magnetizable material, face platepole pieces of magnetizablematerial embedded within and wit-h the sides thereof surrounded b saidface plate frame whereby theface plate pole p-ieces are positioned tocorrespond to the poles on said core piece, and energizing coils adaptedto be carried by the said core pieces.

6. In a magnetic chuck the combination of a vunitary aluminum bodycomprising an open box of non-magnetic material to constitute thehousinglfor the chuck, a core piece of magnetizable material having thebase of vsaid core piece embedded within said aluminum body, polesoutstanding from the said base and'separated from the side walls of saidaluminum body, a face plate comprising an aluminum frame, face platepole pieces of magnetizable material embedded within said aluminum frameand spaced apart to correspond'to the poles on the core piece, andenergizing coils carried by said core piece.

7. In a magnetic chuck in combination an, aluminum body comprising aunitary open box of non-magnetizable material, a core piece having abase provided with extensions, the base of said core piece beingembedded within said aluminum body portion. whereby said extensionssecurely lock said base in position, poles extending from said base,l aface plate comprising a frame of aluminum which surrounds and Supportsthe individual face plate pole pieces, coils on the poles of the corepiece, and means to secure said face plate to said housing.

8. In a magnetic chuck the vcombination of an aluminum body comprisingthe housing, a core piece having the base thereof embedded in saidaluminum body, flat pole pieces extendingLoutwardly from said base,ieces being substantially parallel and exten ing crosswise ofthelongitudinal axis of the housing, the ends of said pole pieces beingsubstantialloioplanar with the y portion, la face plate comprising analuminum frame, face plate pole pieces embedded in said aluminum frameand bei separated one from another by portions o said aluminum frame,said face plate being substantially flat and the pole pleces in saidface plate being positioned to contact with the pole pieces on the corewhen the face plate is in position to cover said housing, coils on thecore pole pieces, and means to secure the face plate to said housing.

9. A magnetic chuck comprising an aluminum body portion, an aluminumface plate, an iron core piece around the base of which said aluminumbody is molded, outstanding pole pieces carried by the base of the corepiece and separated from the sides of the aluminum body, and iron faceplate pole t pieces around which the aluminum face plate frame ismolded, the parts being constructed and arranged so that the chuck issubstantially composed of magnetizable material around which thesupporting housing and face plate of non-magnetizable material ismolded, and: energizing coils adapted when suitably energized tomagnetize th said pole pieces.

10. As an article of manufacture a ma netic chuck body comprisingsuitable po e pieces, electro-magnetic means which when energized areadapted to magnetize said pole pieces, and aluminum means comprising -ahousing for supporting the said pole pieces and the saidelectro-magnetic means.

11. As an article of manufacture a magl netic chuck comprising work-facepole pieces, electro-magnetic means which when energized sultablymagnetize said Work-face pole pleces, and non-magnetizable materlalembedding and supporting said pole pieces and enclosing saidelectro-magnetic means.

12. As an article of manufacture a magnetic chuck comprising Swedishiron workface pole pieces, said pole pieces being spaced apart to bemagnetically separated one from another, electro-magnet1c means whichwhen energized suitably magnetizes the said ole pieces, and a casing ofaluminum in w ich said pole pieces are embedded and which encloses andsupports said pole pieces andl said electro-magnetic means.

13. As an article of manufacture a face plate for magnetic chucks, saidface plate comprising a plurality of face plate pole pieces, and analuminum frame molded around said pole pieces whereby said pole pieceshavetheir sides completely embedded in the said aluminum frame.

14. As an article of manufacture a face plate for magnetic chucks, saidface plate comprising a plurality of face plate polev pieces, and analuminum frame comprising the sole support for said pole pieces wherebysaid pole pieces have their sides ,completely embedded in the saidaluminum frame.

15. As an article of manufacture a face yplate for magnetic chucks, saidface plate pieces of Swedish iron, said pole pieces having work-faces,of substantiallyA tree-like conformation, and having back faces adaptedto conform to suitably electro-magnetic energizing means, said polepieces being ar-4 ranged in a row, and asupporting frame ofnon-magnetizable metal molded Iaround said pole ieces whereby said faceplate is substant1ally integral unit.

17. As an-larticle of manufacture a face plate for magnetic chucks andthe like, saidl face plate comprising a plurality of pole pieces ofSwedish iron, said pole pieces having 'work-faces of substantiallytree-like conformation, and having back faces adapted to conform tosuitable electro-magnetic enerizing means, said pole pieces beingarranged 1n a row, and a supporting frame of nonmagnetizable metalcomprising the sole support for said poleA pieces whereby said faceplate is a substantially integral unit. 1 18. As an article ofmanufacture a face plate for magnetic chucks and the like comprising aYplurality of pole pieces having work-faces of tree-like'conformationwhere-` by the branches from one pole piece are adapted to extendbetween the branches of an adjacent pole, said' pole pieces being setparallel one to another to constitute a row, and an aluminum plate ofthe same thickness as said pole pieces and enclosing and embedding eachpole piece whereby substantially the entire' face plate is.composed ofthe Swedish viron pole piecesand the said aluminum supporting plate. l

19. As an article of'fmanufacture a body portion of a magneticchuckcomprising a core piece of special magnet-mild-steel and being providedwith outstanding pole pieces, i.

and a housing of aluminum molded around the base ofsaid core piece andwith the pole pieces separated from the sides ofthe housing whereby thecore piece and the housing comprise a substantially unitary structure.

20. As an article of manufacture a body for a magnetic chuck comprisinga core piece of magnet-mild-steel, a housing of nonmagnetic materialmolded around .the base of said core piece whereby the said core pieceand said housing comprise substantially a unitary structure.

21. As'an article of manufacture a core piece' for magnetic 'chucks andthe like, said core piece comprising a base, a plurality of flat polepieces outstanding from said base and at substantially rightanglesthereto, the

'mid planes of said pole pieces being substantially parallel.

22. A magnetic chuck comprising a plurality of face plate pole pieces,means to support said pole pieces, and electro-magnetic means tosuitably magnetize said pole pieces, the entire work surface of the face.plate comprising a series of spaced-apart interlocked pole pieces oftree-like conforma- .tion with branches of one pole'piece extendingbetween the branches of the adjacent pole piece. y y

23. A magnetic chuck comprising a plurality of face plate pole pieces,non-magnetic material comprising the means to support to suitablymagnetize said/.pole pieces, the entire work surface of the faceplatecomprising ya series of spaced-apart interlocked pole pieces oftree-like conformation with branches of one pole piece extending betweenthe branches of the adjacent pole piece.

254. A magnetic chuck comprising in combination a housing of aluminum,.aface plate standing pole pieces, face plate pole pieces having a widthgreater than the thickness of the core pole pieces vand embedded withinand carried by said face plate fra-me and in contact with the poles ofthe said ycore, the surface of the faceplate poles, being sub-xstantially coplanar with the surface of the face platerframe, and mea-nscapable when `said pole pieces', and electro-magnetic means esy 4 frameof aluminum, a core having the base thereof. embedded in the base of thesaidy housing, said core .havlng'a plurality of outelectricallyenergized of producing a series of Amagnetic circuits with each circuitthere-- of having a common magnetic line path with the next adjacentcircuit and each .circuit y including a pair of face plate pole pieceswhereby aplurality of complete closed magnetic circuits is formed when amagnetizs,

able work piece rests on the surface plate.

/25. In amagnetic chuck a work-face comprising a plurality ofinterlocking pieces arranged side by' side lwith the length of the polepieces extending'v across the -said work-face, each .pole piecepresenting al holding surface comprising a straight trunk portionwithsquare blocks on each side of said trunk portion to provide atree-like conformation, 'means capable when energized pole ofmagnetizing said pole piecesv to consti- X tute alternate magnetic polesof alternate signs, and a neutral frame for supporting said interlockingpole pieces.'

26.v A face plate for magnetic chucks comprising a plurality of polepieces and a nonmagnetized frame around said pole pieces with portionsof said frame extendingl between said pole pieces to support the same.

27. In a magnetic chuck, the combinationv of. a housing,electromagneticy means within said housing a face plate, a plurality ofpole pieces in said face plate and adapted to be magnetized when saidelectromagnetic means are energized, and asupporting frame surroundingand extending between said pole pieces in such manner that each polepiece is completely surrounded by said frame.

28. A magnetic chuck comprising-in combination a housing, a face platehaving a plurality of individual pole pieces mounted therein.y said polepieces comprising s'ubstantially straight bar-like body portions with aplurality of arms extending outwardly from said body portions with the Y2go arms spaced apart whereby the arms of adjacent pole pieces areinterpositioned, said body portions comprising the under part ofl thepole pieces and the spacing between adjacent pole piece bod portionsbeing greater than the spacing etween adjacent pole piece arms wherebythe magnetic field isI concentrated between the arms when the chuck isenergized, core pole pieces beneath the face plate pole pieces and withthe upper ends of the core pole pieces in contact with said bodyportions of the face plate pole pieces, and coils for energizing thesaid core pole pieces.

29. A magnetic chuck comprising in combination a housing. a face plate.a plurality of face plate pole piecesmounted in the said lface plate.,said face plate pole pieces comprising bar-like body portions and armsextending from said body portions, said arms being spaced apart andbeing arranged in such manner that the arms from adjacent pole piecesare interpositioned, non-mag- `-netic material between the said polepieces,

said body portions comprising the under part of the pole pieces andbeing arranged parallel with the spacing between adjacent body portionsbeing greater than the spacing between adjacent arms whereby themagnetic field is concentrated between the arms. and an electro-magneticmeans for energizing the said pole pieces', the saidelectro-magneticmeans comprising a core piece on the housing and carrying a plurality ofupstandi-ng core pole pieces adapted to contact with the under part ofthe said body portions of the face plate pole pieces, and coils adaptedwhen energized to magnetize the said core pole pieces.

30. As an article of manufacture a pole piece for magnetic chuckscomprising a barlike body portion adapted to form the under part of thesaid pole piece, a plurality oiV outstanding arms extended on each sideof the said body portion and spaced apart in such manner that polepieces of the construction specified maybe arranged with the bodyportions substantially parallel and the outstanding arms of the adjacentpole pieces interspaced, and with the distance between the arms ofadjacent pole pieces being less than the distance between adjacent bodyportions whereby a magnetic field 31. A magnetic chuck having a portionof a work-holding face composed of a plurality of' identicalpole pieces,projections on the pole pieces, and means to support the pole pieces,with the projections of adjacent .pole pieces intel-spaced.

32. A magnetic chuck having a workholding face comprising a plurality ofpole pieces of identically the saine size and Shape arranged oneadjacent to another with extensions t'rom said pole pieces arranged insuch manner thatl the extensions from one polepiece lie between theextensions of an adjacent. pole. piece.

33. A magnetic chuck having a workholdingface comprising a plurality ofpole pieces of identically the same size and shape .arranged oneadjacent to another, non-mag,- netic material surrounding each polepiece, and electromagnetic means capable when energized to magnetizeadjacent poles with opposite magnetic signs.4

34. A magnetic chuck having a workholding face comprising a plurality ofidentical individual pole pieces having body portions and extensionsfrom the body portions, with the extensions from one pole piece lyingbetween the extensions of the adjacent pole piece, and non-magneticmaterial surrounding said pole pieces and isolating the pole pieces onefrom another.

35. A magnetic chuck having a workholding face comprising a plurality ofidentical individual pole pieces having body portions and staggeredextensions from the body portions. with the extensions from one polepiece lying between the extensions o f the adjacent pole piece, andnon-magnetic material surrounding said pole pieces and lisolating thepole pieces one from another.

36. A magnetic chuck having a workholding face comprising a plurality ofidentical individual pole pieces having body portions and extensions onthe work-face side of the body portions, with the extensions from onepole piece lying between the extensions of the adjacent pole piece atthe work Jface, and non-magnetic material surrounding said pole piecesand isolating the pole pieces one from another.

37. A magnetic chuck having a workholding face comprising a plurality ofidentical individual pole pieces having body portions and extensionsfrom the body portions, with the extensions from one pole iece' lyingbetween the extensions of the adjacent pole pieces, and non-magneticmaterial surrounding said pole pieces and isolating the pole pieces onefrom another, the back of said pole pieces being of a different patternfrom the pattern on the work face.

FRANK L. SIMMONS,

